usb: gadget: f_fs: Fix a race condition when processing setup packets.

commit 0aea736ddb877b93f6d2dd8cf439840d6b4970a9 upstream.

If the USB driver passes a pointer into the TRB buffer for creq, this
buffer can be overwritten with the status response as soon as the event
is queued. This can make the final check return USB_GADGET_DELAYED_STATUS
when it shouldn't. Instead use the stored wLength.

Fixes: 4d644abf2569 ("usb: gadget: f_fs: Only return delayed status when len is 0")
Cc: stable <stable@kernel.org>
Signed-off-by: Chris Wulff <chris.wulff@biamp.com>
Link: https://lore.kernel.org/r/CO1PR17MB5419BD664264A558B2395E28E1112@CO1PR17MB5419.namprd17.prod.outlook.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index b17acab77fe2694b5ef82a983080a15863043168..ad7df99f09a4cd87af9003c7c23f4e65ed47cfc7 100644 (file)
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -3403,7 +3403,7 @@ static int ffs_func_setup(struct usb_function *f,
        __ffs_event_add(ffs, FUNCTIONFS_SETUP);
        spin_unlock_irqrestore(&ffs->ev.waitq.lock, flags);
 
-       return creq->wLength == 0 ? USB_GADGET_DELAYED_STATUS : 0;
+       return ffs->ev.setup.wLength == 0 ? USB_GADGET_DELAYED_STATUS : 0;
 }
 
 static bool ffs_func_req_match(struct usb_function *f,